What is the role of ventilation in underground operations?

Without properly sized ventilation, workers may be exposed to a lack of oxygen, a buildup of harmful gases, fumes from internal combustion engines, or excessive heat. These risks can have significant consequences for workers’ health, the continuity of work, and overall site safety.

Without properly sized ventilation, workers may be exposed to a lack of oxygen, a buildup of harmful gases, exhaust fumes from internal combustion engines, or excessive heat. These risks can have significant consequences for the health of the workforce, the continuity of operations, and the overall safety of the job site.

What are the three objectives of ventilation?

Ventilation in underground structures serves three fundamental objectives:

• to replenish the oxygen essential for breathing;
• to dilute and remove pollutants present in the air;
• to remove heat in order to maintain a temperature suitable for workers.

These three functions are complementary. Depending on the nature of the construction site, however, one of them may take priority and dictate the design of the ventilation system.

Why is it necessary to renew the oxygen in the air?

Oxygen is essential for workers to breathe and for the operation of much of the equipment found on underground job sites. In a confined space, renewing the oxygen is essential to maintaining a safe atmosphere.

Why is a drop in oxygen levels dangerous?

Continuous monitoring of air quality is therefore essential in underground structures to prevent any risks associated with oxygen deficiency.

Why is it necessary to dilute gases and dust?

In addition to replenishing oxygen, ventilation also removes pollutants produced by construction activities or naturally present in certain soils.

Immediate effects

• Carbon monoxide;
• Carbon dioxide;
• Nitrogen oxides;
• Hydrogen sulfide;

Long-Term Effects of Dust and Gases in Underground Environments

Unlike certain toxic gases, whose effects can be immediate, other pollutants present in underground structures pose chronic risks. Repeated exposure, even at low concentrations, can lead to respiratory diseases or serious health conditions that sometimes develop several years after exposure.This is why ventilation also plays a vital role in preventing occupational diseases.

Crystalline Silica Dust

Operations such as drilling, excavation, crushing, or sawing rock generate very fine dust that sometimes contains respirable crystalline silica.
Invisible to the naked eye, these particles penetrate deep into the lungs when inhaled. The body cannot eliminate them naturally, which gradually causes inflammation and then irreversible damage to lung tissue.
Prolonged exposure can lead to:

• silicosis, a chronic lung disease that progressively reduces respiratory capacity;
• an increased risk of chronic obstructive pulmonary disease (COPD);
• an increased risk of developing certain types of lung cancer, as recognized by health authorities.

Reducing dust concentrations through proper ventilation is therefore a key component of collective worker protection.

Pneumoconioses

The term “pneumoconiosis” refers to a group of lung diseases caused by the repeated inhalation of mineral dust during occupational activities.
In underground work, this dust can come from various types of rock that are excavated or from materials handled during excavation operations.
Over the years, these particles accumulate in the lungs and cause fibrosis: that is, a gradual stiffening of lung tissue. This progression leads in particular to:

• increasingly severe shortness of breath;
• a decrease in respiratory capacity;
• chronic fatigue upon exertion;
• a lasting impairment of quality of life.

Since these diseases are irreversible, prevention relies primarily on limiting exposure through effective ventilation systems, combined with other collective protective measures.

Radon

Radon is a naturally occurring radioactive gas produced by the decay of uranium found in certain geological formations.
Colorless, odorless, and undetectable without specialized equipment, it can accumulate in confined spaces when air exchange is insufficient.
Prolonged exposure to high concentrations significantly increases the risk of developing lung cancer, particularly among people exposed over many years.
In underground structures, managing radon risk relies on several complementary measures:

• A preliminary assessment of the site’s geological characteristics;
• Regular monitoring of concentrations when necessary;
• A ventilation system capable of ensuring effective air exchange to prevent any buildup.

Why is it necessary to remove heat?

Temperatures naturally rise in underground structures. Without ventilation, this heat gradually builds up and can make working conditions difficult, or even dangerous.

The main sources of heat

🌍 natural heat from the ground;
🚜 diesel engines;
⚡ electrical equipment;
💥 blasting;
💧 water seepage;
📏 depth of the structures.

In summary

Ventilation in underground environments is not merely about circulating air. It ensures the safety of workers, improves their working conditions, and enables excavation operations to proceed smoothly.
Depending on the characteristics of the job site, the design of the ventilation system will be primarily dictated by one of the following factors:

• the presence of gases;
• the natural heat of the ground;
• emissions from diesel-powered machinery;
• dust generated by the excavation work.

Since every project is unique, an airflow study is conducted to determine the required airflow rate, the equipment to be used, and its layout to ensure effective ventilation that complies with safety requirements.

Frequently Asked Questions